#include "postgres.h"

#include "fmgr.h"
#include "plpython.h"
#include "plpy_typeio.h"
#include "hstore.h"

PG_MODULE_MAGIC;

extern void _PG_init(void);

/* Linkage to functions in plpython module */
typedef char *(*PLyObject_AsString_t) (PyObject *plrv);
static PLyObject_AsString_t PLyObject_AsString_p;
#if PY_MAJOR_VERSION >= 3
typedef PyObject *(*PLyUnicode_FromStringAndSize_t) (const char *s, Py_ssize_t size);
static PLyUnicode_FromStringAndSize_t PLyUnicode_FromStringAndSize_p;
#endif

/* Linkage to functions in hstore module */
typedef HStore *(*hstoreUpgrade_t) (Datum orig);
static hstoreUpgrade_t hstoreUpgrade_p;
typedef int (*hstoreUniquePairs_t) (Pairs *a, int32 l, int32 *buflen);
static hstoreUniquePairs_t hstoreUniquePairs_p;
typedef HStore *(*hstorePairs_t) (Pairs *pairs, int32 pcount, int32 buflen);
static hstorePairs_t hstorePairs_p;
typedef size_t (*hstoreCheckKeyLen_t) (size_t len);
static hstoreCheckKeyLen_t hstoreCheckKeyLen_p;
typedef size_t (*hstoreCheckValLen_t) (size_t len);
static hstoreCheckValLen_t hstoreCheckValLen_p;


/*
 * Module initialize function: fetch function pointers for cross-module calls.
 */
void
_PG_init(void)
{
    /* Asserts verify that typedefs above match original declarations */
    AssertVariableIsOfType(&PLyObject_AsString, PLyObject_AsString_t);
    PLyObject_AsString_p = (PLyObject_AsString_t)
        load_external_function("$libdir/" PLPYTHON_LIBNAME, "PLyObject_AsString",
                               true, NULL);
#if PY_MAJOR_VERSION >= 3
    AssertVariableIsOfType(&PLyUnicode_FromStringAndSize, PLyUnicode_FromStringAndSize_t);
    PLyUnicode_FromStringAndSize_p = (PLyUnicode_FromStringAndSize_t)
        load_external_function("$libdir/" PLPYTHON_LIBNAME, "PLyUnicode_FromStringAndSize",
                               true, NULL);
#endif
    AssertVariableIsOfType(&hstoreUpgrade, hstoreUpgrade_t);
    hstoreUpgrade_p = (hstoreUpgrade_t)
        load_external_function("$libdir/hstore", "hstoreUpgrade",
                               true, NULL);
    AssertVariableIsOfType(&hstoreUniquePairs, hstoreUniquePairs_t);
    hstoreUniquePairs_p = (hstoreUniquePairs_t)
        load_external_function("$libdir/hstore", "hstoreUniquePairs",
                               true, NULL);
    AssertVariableIsOfType(&hstorePairs, hstorePairs_t);
    hstorePairs_p = (hstorePairs_t)
        load_external_function("$libdir/hstore", "hstorePairs",
                               true, NULL);
    AssertVariableIsOfType(&hstoreCheckKeyLen, hstoreCheckKeyLen_t);
    hstoreCheckKeyLen_p = (hstoreCheckKeyLen_t)
        load_external_function("$libdir/hstore", "hstoreCheckKeyLen",
                               true, NULL);
    AssertVariableIsOfType(&hstoreCheckValLen, hstoreCheckValLen_t);
    hstoreCheckValLen_p = (hstoreCheckValLen_t)
        load_external_function("$libdir/hstore", "hstoreCheckValLen",
                               true, NULL);
}


/* These defines must be after the module init function */
#define PLyObject_AsString PLyObject_AsString_p
#define PLyUnicode_FromStringAndSize PLyUnicode_FromStringAndSize_p
#define hstoreUpgrade hstoreUpgrade_p
#define hstoreUniquePairs hstoreUniquePairs_p
#define hstorePairs hstorePairs_p
#define hstoreCheckKeyLen hstoreCheckKeyLen_p
#define hstoreCheckValLen hstoreCheckValLen_p


PG_FUNCTION_INFO_V1(hstore_to_plpython);

Datum
hstore_to_plpython(PG_FUNCTION_ARGS)
{
    HStore       *in = PG_GETARG_HS(0);
    int            i;
    int            count = HS_COUNT(in);
    char       *base = STRPTR(in);
    HEntry       *entries = ARRPTR(in);
    PyObject   *dict;

    dict = PyDict_New();

    for (i = 0; i < count; i++)
    {
        PyObject   *key;

        key = PyString_FromStringAndSize(HSTORE_KEY(entries, base, i),
                                         HSTORE_KEYLEN(entries, i));
        if (HSTORE_VALISNULL(entries, i))
            PyDict_SetItem(dict, key, Py_None);
        else
        {
            PyObject   *value;

            value = PyString_FromStringAndSize(HSTORE_VAL(entries, base, i),
                                               HSTORE_VALLEN(entries, i));
            PyDict_SetItem(dict, key, value);
            Py_XDECREF(value);
        }
        Py_XDECREF(key);
    }

    return PointerGetDatum(dict);
}


PG_FUNCTION_INFO_V1(plpython_to_hstore);

Datum
plpython_to_hstore(PG_FUNCTION_ARGS)
{
    PyObject   *dict;
    volatile PyObject *items_v = NULL;
    int32        pcount;
    HStore       *out;

    dict = (PyObject *) PG_GETARG_POINTER(0);
    if (!PyMapping_Check(dict))
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("not a Python mapping")));

    pcount = PyMapping_Size(dict);
    items_v = PyMapping_Items(dict);

    PG_TRY();
    {
        int32        buflen;
        int32        i;
        Pairs       *pairs;
        PyObject   *items = (PyObject *) items_v;

        pairs = palloc(pcount * sizeof(*pairs));

        for (i = 0; i < pcount; i++)
        {
            PyObject   *tuple;
            PyObject   *key;
            PyObject   *value;

            tuple = PyList_GetItem(items, i);
            key = PyTuple_GetItem(tuple, 0);
            value = PyTuple_GetItem(tuple, 1);

            pairs[i].key = PLyObject_AsString(key);
            pairs[i].keylen = hstoreCheckKeyLen(strlen(pairs[i].key));
            pairs[i].needfree = true;

            if (value == Py_None)
            {
                pairs[i].val = NULL;
                pairs[i].vallen = 0;
                pairs[i].isnull = true;
            }
            else
            {
                pairs[i].val = PLyObject_AsString(value);
                pairs[i].vallen = hstoreCheckValLen(strlen(pairs[i].val));
                pairs[i].isnull = false;
            }
        }
        Py_DECREF(items_v);

        pcount = hstoreUniquePairs(pairs, pcount, &buflen);
        out = hstorePairs(pairs, pcount, buflen);
    }
    PG_CATCH();
    {
        Py_DECREF(items_v);
        PG_RE_THROW();
    }
    PG_END_TRY();

    PG_RETURN_POINTER(out);
}
